1. Field of the Invention
This invention relates to the field of stock estimation of underwater resources by underwater tagging of representative animals, and in particular to a method, system, and apparatus that utilizes new and existing equipment for capturing and tagging of marine fauna in their underwater environment.
The invention is intended for use in the environment of a fishing type vessel equipped with a conventional trawl and cable wire, with tagging equipment constructed according to this invention placed in the fishing gear to capture and constrain an aquatic animal and then tag it with, for example, an active electronic tag or a tag identified by a number (ID-number). Utilizing existing equipment reduces the complexity of equipment used to establish underwater tagging. Yet, it still provides an advanced and economic method for tagging, as well as money-saving communications capabilities between the vessel and the tagging equipment via the transfer of video and control signals to and from the tagging equipment. Thus, the status of moveable items can be visualized, and measured data transferred.
2. Description of Related Art
In order to better estimate the condition of underwater resources, including sea, ocean, and freshwater fauna, it is of vital importance to tag these animals, and thereby track migration and distribution patterns, particularly in relation to environmental conditions. The environmental conditions that influence an animal's migration patterns or behavior are important parameters in modeling and/or simulation of underwater resources, and study of the animal's reactions to these parameters is critical if future resource estimation is to be improved.
Tagging marine fauna in its own natural environment decreases the influence of the tagging on the animal and increases the survival rate of the animals.
Tagging underwater fauna in its own natural environment makes it possible to tag deep-sea species that it would be impossible to tag otherwise, since such species could not survive being surfaced for tagging by conventional methods.
Tagging has been performed for many years by catching marine fauna and surfacing them, where these animals are anaesthetized, tagged with a tag bearing information, observed and released. The survival capability of these tagged fish is influenced by a number of parameters such as temperature changes, pressure changes, handling, medical treatment, and, after a successfully tagged subject has been released, exposure to temperature and pressure changes once again. The treatment is, in itself, a disturbance to the animal, and the fish could well become an easy prey for other marine fauna after being released.
Tagging also has been performed underwater at depths where marine fauna are located, but these systems usually involve the use of a trap to capture the animal while a diver positioned adjacent the trap performs a tagging procedure. Obviously, the necessary presence of a diver results in relatively high costs associated with the tagging procedure and the number of animals that can be tagged is limited by the rate at which the divers can perform the tagging procedure as well as the available time for each diver to perform the procedure at the depths where the animals have been trapped.
There are many species today that, because of their lifestyle, cannot be tagged by conventional methods. One of these is the highly commercially important species of redfish, Sebastes marinus. The redfish is classified as a pelagic or bottom fish, and because of its physiological make-up, it cannot compensate for the pressure change when taken from its natural habitat (300 to 800 meters) in water to the atmospheric pressure of air. Because of this, the redfish has never been tagged and therefore there are many questions unanswered concerning its general biological behavior. This problem exists with other deep-sea species as well and, even if the fish can tolerate the pressure difference, the released, tagged fish is not necessarily healthy and its normal life expectancy cannot be relied on.